The proposed research addresses the gap in knowledge between nutritional status of an organism and the response of its genetic material. Nutritional stimuli influence the structure as well as the function of liver chromatin. I have previously studied how rat liver chromatin responds to varying intakes of carbohydrates, protein, and fat and have demonstrated (J. Nutr. 110:105, 1980) that the relationship of dietary components alters the highly ordered structure of chromatin. The specific objectives of this proposal are (1) to determine by what manner nutritional stimuli alter the structure of liver chromatin, (2) to determine whether differences exist in the complexity and abundance classes of messenger RNA (mRNA) populations under various nutritional states, and (3) to determine whether there are modifications in chromosomal protein constituents of chromatin. To determine how nutritional intake alters chromatin structure, chromatin from purified nuclei will be mildly digested with micrococcal nuclease (E.C.3.1.4.7). The fragments generated will be analyzed as to size by polyacrylamide gel electrophoresis and as to sequence organization by DNA-DNA reassociation. The complexity of mRNA populations will be determined by RNA-DNA hybridization. Chromosomal proteins associated with chromatin fragments generated from nuclease incubation will be purified and analyzed by two-dimensional gel electrophoresis.